US2101534A - Urea-formaldehyde condensation products - Google Patents

Description

a w- 1 1 1 i 2,101,534.

UREA-FORMALDEHYDE CONDENSATIQN i PBODUCTSIQ M DonaldEdwards Edgar, Phlladelphlarrau. assign- Y M or.to ,l l.fl. v du Pont deNemours & Company,

i .wilmingtonfiDel 'a corporation .of Delaware No Drawing. Application-August i, 1935, i 1 'SerialNo. 34,300 i c c A L l (01.260 3) I Thiswinvention relates io condensation prodsodium acid phosphate (NaHzPO il 511 buffer;

ucts of -urea and :formaldehyde, andi more -'par- The hydrogen ion concentration of the solution ticularly toan improved procedure for preparis then adjustedto a pH value of 7.6 by the addiing dimethylol urea in a physicalcondition more "tion of sodium hydroxide solution "using Phenol satisfactory for further use. l n Redas an indicator and comparing; with standard 5 The'reaction product of urea" and 5 aqueous color tubes. The ur'ea is thenflissdlved'in the formaldehyde ordinarily precipitates as a white formaldehyde solution thus prepaiedfThe liquid erystalline solidwhich.isreadily'soluble in water. is keptrat a temperatureof b'elo'w 25 1C., and i c The bulk of the aqueous material is usually repreferably not below 15 C.,by any suitable means 10 moved by filtration and the white crystalline and allowed tostand for at least 48 hours or 10 preoipitateis then dried usually at ordinary room until complete precipitation of the reaction prodtemperatures or at elevated temperatures under uct has taken place. Precipitation usually begins 3 controlled conditions. yThe drying of the crystalafter about '12 hours standing. When theprecipiline mass offers .difliculties in that the crystals tation is complete the crystalline material is recakeyin hard lumps which delays the drying time moved by filtration. The crystalline mass is then 15 considerably, thus making the operation ineftreated with ethyl; alcohol to form a slurry and flcientl This caking of the crystals is probably. again filtered to remove the alcohol; This operadue to the cementing action of the'dissolved portion is preferably carried out two times. After tion of the crystals from which the aqueous mathe last treatment and removal of as much alcohol terial has not been completely removed during as possible by filtration the material may be dried 20- the filtering operation. The material thus proby any convenient means either at room temperaduced inhard lumps and cakes presents difiiculture or at a slightly elevated temperature. The ties for further use, requiring grinding and crystalline mass thus prepared dries completely screening or sieving, The material thus prepared and thoroughly and results in a fluffy material is often not thoroughly dry and must here-dried substantially free from any lumps and caking.

. after grinding and screening. Instead of.aqueous formaldehyde I may use h e tio h s a O j the provision Dara-formaldehyde. In this case the urea is dis: of an improved procedure for preparing'the resolved inwater and the para-formaldehyde added action product of urea and formaldehyde. A furas a solid. i

ther object is the provisionoi an improved pro- In place of the ethyl alcohol which is used to 30 cedure for preparing dimethylol urea in a physlwash the crystalline mass after filtration, methyl,,

cal condition inwhich it will be more satisfactory propyl, butyl or other similar aliphaticalcohols '0 fu th imm d 8-. A further ject is as well as such materialsas acetone, ethyl ether the provision of. an improved method for the prepof ethylene glycol, methyl ether of ethylene glycol aration of .dimethylol urea which will obviate the and similar materials may housed, the principal 5 ss y of th us f d asti rindin procedures requirement being that the liquid is miscible with i to place the material in condition for further use, water,

and which will produce a material'of uniform- If desired the crystalline mass, after the al- .quality and relatively uniform physical condition. oohol treatment, may be treated with a liquid 40 Otherobjects will appear hereinafter. l which is miscible with the alcohol used and which 40 The o j ar mpli h d. y rem vin does not react with the product of the reaction as much water from the crystalline precipitate as f rea, and formaldehyde. Among such liquids practical y fil ra ion, breaking the resulting may be, mentioned the aromatic hydrocarbons cake into Small pieces, treating Wi h a iq i such as benzol, toluol and xylol, and aliphatic miscible with Water but a non-solvent f0! the hydrocarbons as petroleum ether, gasoline, naph. 45

urea-formaldehyde reaction products, filtering thas and the like. and drying. i The washing with alcohol may be repeated any The following example isillustrative of a pre number of times as may be found practical; A

ferred embodiment of the invention: convenient modification for the washing of the Exampz 1 crystalline mass may comprise centrifuging in a 50 Grams basket type centrifuge and after the bulk of the v aqueous material is removed spraying with the i liquid to remove the remaining aqueous material p I i as may adhere to the crystalline mass. Many To theaqueous formaldehyde,v solutionis added variations in this respect will be readily apparent 55 to those skilled in the art. While the hydrogen ion concentration given in the example above is noted as 1.6, this may conveniently range between 6 and 9, yielding equally satisfactory results and without departing from the spirit of the invention The material produced according to the procedure of the invention may be advantageously adapted for use as a moldingmaterial, as such, ccording to methods well known in the art. Further, the material may be adapted for use as a film-forming composition for particular purposes either alone or in combination withv other.

synthetic resins and/or suitable softening agents.

This invention presents as a principal advantage a method for producing the reaction product of urea and formaldehyde, which can be more readily and efliciently dried after the removal of the aqueous liquid by filtration and which does not substantially cake or harden into lumps on drying. The reaction product of urea and formaldehyde produced in accordance with the present invention is more stable than material produced by present procedures, i. 6. dried directly after filtration. The product made by myimproved method, as compared to the urea-formaldehyde reaction product as conventionally made, is also in a much more suitable physical condition for further use where it may be desired to dissolve it or react with other materials withthe urea and formaldehyde in aqueous solution thereby obtaining in caked form a crystalline precipitate of said reaction product in aqueous liquor which is a non-solvent for the precipitated reaction product, separating substantially all said aqueous liquor from the crystalline caked precipitate, breaking the resulting cake into small pieces, then forming a slurry of said precipitate with a water miscible liquid which is selected from the class consisting of acetone and alcohols and which is a non-solvent'for said precipitate, separating said precipitate from the non-solvent. and completely drying the precipitate thereby obtaining said urea-formaldehyde reaction product in a fiufi'y form substantially free from lumps and caked particles.

DONALD EDWARDS EDGAR.